Probably not difficult, but installations vary so much it's difficult to say. Depends more on the particular trailer than the genset. You need to deal with the exhaust, and the fuel line if its plumbed to the RV's LP system. The latter should be simple, in any case. How does the electric power get to the trailer? Do you plug into the genset outlet, or is there some other power transfer, e.g. an auto switch? That could complicate things.

The rest should be just some bolts around the base of the genset, but getting at them could be a challenge if the trailer was built around the genset. If the genset was an add-on, then its probaby easy enough.

You probably want to move the transfer switch with the genset. Just pull the ATS out and connect the shore cord direct to the feeder to the main load center. You will need a junction box to contain the splice.

You can cap off the LP line at either the genset end or at Tee into the tanks. It would probably be best to try to move the LP line and tee to the new trailer. Fittings to splice the LP lines together after removing the Tee are standard hardware items and readily available. Your local hardware store should have them.

Thanks for your advice. I ended up leaving the generator because I figured it would sell faster, and it did. We recently bought our nash 25C (generator ready) and I just ponied up and bought a Honda 2000w peak with a 26ish amp output plug ($1k). If the power goes out in the winter I gotta have heat. RV dealer fellow said installing a propane genny is about $3k.